Numerical simulation and field tests of minimum-tillage planter with straw smashing and strip laying based on EDEM software
The advanced and comprehensive utilization and entire burning prohibition of fully covered crop straw in farmlands have become significant in modern agriculture. Considering the high straw-returning yields, complicated operating procedures, and tight crop-stubble rotation, as well as high power consumption, poor smoothness shun, and low multiple-seed index obtained using traditional compound operation machines for rice and wheat rotation regions in the middle and lower reaches of the Yangtze River, this study extends the concept of the new ‘clean-area planting’ pattern. A minimum-tillage planter with straw smashing and strip laying was developed for full straw mulching fields. In a single pass, the planter could complete multiple operation processes, including straw-stubble smashing, seed-belt cleaning, inter-row stacking, seed-bed treatment, fertilization sowing, and soil covering and suppression. A mechanical model for the straw particle was established using the discrete element method (DEM) and EDEM software, and DEM virtual simulation tests and numerical analysis were conducted. A quadratic rotating orthogonal center combination test was implemented by setting the smashing spindle speed n′(A), machine ground speed v(B), and rotation tilling spindle speed n(C) as the influence factors, with the straw mulch uniformity ε1 and the coefficient of straw ridge disturbance ε2 as the evaluation indices. Response surface optimization analysis was performed to obtain the optimal combination of operational parameters affecting the planter working performance. The results indicated that the most significant factors affecting the straw mulch uniformity, ε1, and coefficient of straw ridge disturbance, ε2, were: smashing spindle speed, n′, > machine ground speed, v, > rotation tilling spindle speed, n, and rotation tilling spindle speed, n, > machine ground speed, v, > smashing spindle speed, n′. The optimal combination of these operational parameters was n′ = 2042.35 r/min, v = 0.99 m/s, and n = 440.93 r/min, providing a maximum ε1 = 94.30% and minimum ε2 = 9.67%. Field verification test results indicated that the optimized minimum-tillage planter achieved mean values of ε1 = 86.25% and ε2 = 9.75%, with average relative errors of 8.51% and 10.27% compared to the simulation tests, respectively. The accuracy and effectiveness of the DEM simulation model were verified. Moreover, the stipulated industry standards and operation requirements of no-tillage planter machinery with a straw-returning field can be satisfied, and technical support can be provided for follow-up studies of similar conservation tillage equipment.
Keywords: Inter-row stacking, Clean-area planting, Discrete element method, Field validation test